Question

20x+15x+20(x-1)+15(x-1)=245

Answer 1

x=4

Answer 2

if you want check plug in the 4 where ever you see an x

Answer 3

add the x's first
20x+15x+20x-20+15x-15=245
70x-35=245
70x=245+35
70x=280 <-- now divide 70 on both sides
x=4