please can someone answers this math question.should be quite easy because it is year 7 math.?

Question

find x:(a)3:2=5:x
b)4:3=x:4
c)x:7=1:2
and

find each ratio in the form 1:n,giving n to 3 significant figures where necessary:
a)25:10000
b)2:15

please can you tell me how you got the answers and tell me the workings.Thank you.

PS:I mean it should be easy for you because i'm in year7 and i know most of the people that read this will be a lot higher than that

Answer 1

when you have a:b=c:d

for the purposes of these problems, ":" means the same as division, this means you just have to solve algebraically by getting x by itself.

a) 3:2=5:x think of 3/2=5/x

divide by 5

x=3/2/5
=3/2*1/5= 3/6=.5, x=.5

b)4/3=x/4
multiply by 4
x = 16/3

c) x/7=1/2
multiply by 7
x=1/2*7=3.5

a) so now it's just simplifying a fraction
where 25/10000
can be simplified by dividing top and bottom by 25
so you have
25:10000
top/25=1
bottom/25=400
=1/400=1:400

b) the same , this is simplest form but you want the top to be 1, even though you can't divide to get a whole number,

so it's just 1:7.5

so its just

Answer 2

when 2 ratios are equal, as in a/b = c/d, then cross products are equal: ad = bc. when written as a:b = c:d, we say the product of the means, bc, equals the product of the extremes, ad. so,
a) 3:2 = 5:x, 3x = 10, x = 10/3
b) 4:3 = x:4, 3x = 16, x = 16/3
c) x:7 = 1:2, 2x = 7, x = 3.5

a) just like simplifying fractions, 25:10,000 = 1:400
b) 2:15 = 1:7.5

Answer 3

(a)3:2=5:x --> 2*5 = 3x --> x = 10/3 = 3 1/3
b)4:3=x:4 --> 3x = 4*4 --> x = 16/3 = 5 1/3
c)x:7=1:2 --> 7*1 = 2x --> x = 7/2 = 3 1/2

a)25:10000 = 1/ 400
b)2:15 = 1 /7.5

Answer 4

a) 2/3*5=10/3
b) 4/3*4= 16/3
c) just look at it = 7/2

1= 25/25 = 1
n= 10000/25 = 400
1:400

1 = 2/2 = 1
n = 15/2 = 7.5
1:7.5

Answer 5

if its quite easy...YOU do it