Question

5a – 10b = 45, when b = 3

Answer 1

5a - 10b = 45 when b = 3, then

5a - (10*3) =45
5a - 30 = 45
5a = 45+ 30
5a = 75
a = 75/5
a =15

Answer 2

Well, since you have the value of b, the first thing you want to do is substitute that value in for b.

5a - 10(3) = 45

10*3 = 30

5a - 30 = 45

Now, to get the variable by itself (a) you have to + 30 because you have to reverse the subtraction.

5a = 75

Now, you divide by 5 to finish getting a by itself.

a = 15

Hope this helps!