math
posted by geekgirl95 on .
shanon needs 20g of 80% of gold to make a pendan. she has some 85% gold and some 70% gold, from broken jewelry and wants to know how much she should use. determine the quantity of each alloy that she should use.

amount of 85% gold > x g
amount of 70% gold > 20x
solve for x :
.85x + .7(20x) = .8(20) 
thanks :)