math help.......?

Question

question 1)
she buys a pair of trainers which cost $63.40 plus 10% tax. work out the cost?

question 2)
He runs 100m in 12.5 seconds... what is his average speed?

question 3)
3k-2=13
k= ??

question 4)
4t-2=2t+6
t= ???

please help....
and can u explain how u did it that would help me alot!!!

thanx
xoxo

Answer 1

1). All you have to do with this problem is take the cost of the trainers which is $63.40 and multiply that by 10%. 10% in decimal form is .10. If you don't know how to put a percent in decimal form all you have to do is take the percent and divide it by 100. 10/100 will give you 1/10 and if you divide 1 by 10 you will get .1. after you multiply $63.40 by .10 you should get 6.34. Add 6.34 to $63.40 to give you the total cost which ends up being $69.74.

2). For this problem speed = distance/time. Divide 100m by 12.5 seconds to give you 8m/s.

3. In this problem you want to isolate k so the first thing you have to do is add 2 to both sides of the problem to get 3k by itself:

3k - 2 = 13
3k = 15 ---> Now divide both sides by 3 to get k by itself.

k = 5

4). In this problem you want to combine like terms so that you can isolate t and get your answer.

4t - 2 -2t = 6
2t - 2 = 6-----> Add 2 to both sides to get 2t by itself

2t = 8 ----> Again, divide both sides by 2 to get t by itself

t = 4 -----> If you want to check your answer to make sure that it is correct all you have to do is substitute your answer into your equation and see if both sides equal. In this case your answer is 4 so lets check your answer:

4(4) - 2 = 2(4) + 6
14 = 14 ---> your answer checks.

Answer 2

Q1) $63.40 divided by 10 gives you the 10% ($6.34)
Add the two together to get your answer - £69.74

Q2) distance covered divided by time taken (100m divided by 12.5 seconds) = 8mps (8 meters per second)

Q3)the question says '3 times k - 2 = 13'
so firstly remove the '-2' by adding it to the 13 (making 15)
the question is now 3 times k = 15.
So reverse the question to get 15 divided by 3 = k (5)
So the answer is 5

Q4) again get rid of the -2,
so the question would then be '4 times t = 2 times t plus 8'
then you can get rid of the common values, so you can get rid of any value on the left side of the '=' as long as you get rid of the same value on the right side of the '='... so if we get rid of the '2 times t' on the right hand side the question then becomes '2t = 8' or '8 divided by 2 = t' (4)
so the answer is 4

Hope I didn't confuse you with the explanations. Basically it is called balancing the equation. Any alteration made to the left side of the '=' needs to be mirrored in the right side of the '='

Answer 3

1. 63.40 x 10% tax=
63.4 x .10=$ 6.34= 63.40+6.34=$69.74

2. 100m in 12.5 seconds
100/12.5= 8 meters/second

3. 3k-2=13
3k-2+2=13+2
3k=15
k=5

4. 4t-2=2t+6
4t-2t-2=2t-2t+6
2t-2=6
2t-2+2=6+2
2t=8
t=4

Answer 4

well well well..
1) 10%= 0.1, so 0.1*63.40= $6.34 tax
the final cost is 6.34 + 63.40 = $69.74

2) speed= distance /time
so, it's u=8 m/sec

3) 3k-2=13
3k=13+2
3k= 15
k= 15/3 = 5

4) 4t-2=2t+6
4t-2t= 6+2
2t= 8
t= 8/2= 4

Answer 5

Answer 1:
$63.40 x 10% = $6.34
Therefore, total cost = $63.40+$6.34 = $69.74

Answer 2:
100m/12.5s = 8m/s

Answer 3:
3K-2=13
Adding 2 on both sides;
3K-2+2=13+2
3k=15
k=15/3=5

Answer 4:
4t-2=2t+6
Adding -2t on both sides;
4t-2-2t=2t-2t+6
2t-2=6
2t=6+2
2t=8
t=8/2=4

Answer 6

To find the total cost, take the cost and multiply by 1.10 (110%) or multiply the cost by the tax (.10) and add that amount to the cost.

To find average speed, divide the distance ran by the time.

For #3 and #4- You need to isolate the variable (k or t) to one side, then solve for the variable.