7x = 3y
y = 35
plug in 35 for y
7x = 3(35)
simplify, multiply 3 and 35 together
3(35) = 105
7x = 105
isolate the x, divide 7 from both sides
7x/7 = 105/7
x = 15
15, A is your answer
For #2:
Bruce has 97 sports card. 34 are football cards. Find y, which are the amount of sports cards not foot ball cards
34 + y = 97
34 (-34) + y = 97 (-34)
y = 97 - 34
y = 63
hope this helps
