Question 124567
.8(x+10)+.5x=.7(2x+10)
.8x+8+.5x=1.4x+7
.8x+.5x-1.4x=7-8
-.1x=-1
x=-1/-.1
x=10 pounds of $.50 coffee is used.
10+10=20 pounds of $.80 coffee is used.
proof
.8*20+.5*10=.7*30
16+5=21
21=21