how do u solve 3a + b= 7 and a-b = 10?

Answer 1

Add the 2 equations

4a = 17
a = 17/4 = 4.25
b = a-10 = -5.75

Answer 2

Use the process called "elimination." Write the equations as follows and simply add together the two equations, and you'll see that the b's cancel out:

3a + b = 7
+ a - b = 10
-----------------
==> 4a = 17 (divide by 4)
==> a = 17/4

Now, plug into the second equation:

a - b = 10
(17/4) - b = 10
17/4 - b = 40/4
17/4 - 40/4 = b
b = -23/4

So, you have that a = 17/4 and b = -23/4.

Answer 3

add the two equations to remove one of the variables :
(3a+b) + (a-b) = 7 +10
so 4a = 17, a=17/4
a-b = 10 so b = a-10
a-10 = 17/4 - 40/4 = -23/4

Answer 4

by substitution method
3a+b=7 (i) a-b=10 (ii)
a=10+b
put value of a in equation 1
3(10+b)+b=7
30+3b+b=7
4b= -23
b= -23/4 value of B

PUT VALUE OF B IN EQUATION (II)
a= 10 - 23/4 take L.C.M
a= 40-23/4
a=17/4

Answer 5

make the second one a=10 + b
substitute that in in the first equation.
3(10 + b) +b =7
30 + 3b +b =7
30 +4b=7
4b=-23
b=-5 3/4

now plug that back in and say a + 5 3/4 =10
a=4 1/4

Answer 6

4a = 17
a = 17/4
b = 7 - 51/4
b = 28/4 - 51/4
b = - 23/4
Solution is a = 17/4 , b = - 23/4

Answer 7

ok its algebra.

first, 3a+b=7
first you have to multiply 3 by a negative number so what number times three makes it low enough so you could add another and make 7?

so a=-3, b= 16.

second honestly it's easy.

A=-20 b=10.

Answer 8

3a+b=7
3(2)+(1)=7

a-b=10
(20)-(10)=10
(40)-(30)=10

u got too many variables