Question 245928
let a= Anne's age
let b= Bill's age
a=(7/10)*b -their ages now

a+4=(8/11)*(b+4) -their ages in four years
Substitute (7/10)*b for a in the second equation
(7/10)*(b)+4=(8/11)*(b+4)
multiply both sides by 110 (10*11)
77*b+440=80*(b+4)
77*b+440=80*b+80*4
77*b+440=80*b+320
subtract 320 from both sides
77b+120=80b
subtract 77b from both sides
120=3b
divide both sides by 3
40=b Bill is 40 years old
a=(7*40)/10
a=7*4=28
check
32=(8/11)*(44)
32=8*4=32
ok