algebra
posted by john on .
mary went to the store for some fruit. The apples were $1.00 per pound and the oranges were $0.50 per poumd. She spent $5,00 all together and took home a total of 8 pond of fruit. How many ponds of apples and oranges did she buy?

Let O and A stand for pounds of fruit.
O + A = 8
A = 8  O
.5O + A = 5
Substitute 8O for A in third equation and solve for O. Insert that value into the first equation and solve for A. Check by inserting both values into the third equation.