<PRE><B>Question 358715</B>
.50X+.19*30=.40(30+X)
.50X+5.7=12+.40X
.50X-.40X=12-5.7
.10X=6.3
X=6.3/.10
X=63 GALLONS OF 50% ACID SOLUTION IS USED.
PROOF:
.50*63+.19*30=.40(30+63)
31.5+5.7=.40*93
37.2=37.2

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