math
posted by emmy on .
Yuki's age is four years more than onefourth of Xena's age. Xena's age is 21 years and 6 months more than seveneighths of Yuki's age. How old are Xena and Yuki?

y = .25x + 4
x = 7/8y +21.5
Substitute .25x+4 for y in second equation and solve for x. Insert that value into the first equation and solve for y. Check by inserting both values into the second equation.