12.5=0.8x first you have to divide 12.5 by 0.8 X=15.625

7(x-9)=4x-36 first do distributive property for 7(x-9) 7x-63=4x-36 second you minus 4x from each side 3x-63=-36 next you add 63 on each side 3x=27 last u divide 3 on each side X=9