Selam N. answered • 09/13/15

Mathematics Teacher

Let x represent the 90% antifreeze solution to be added

therefore, the amount of antifreeze in this solution will be (90%)(x)

The amount of antifreeze in the 100 gallons solutions is (10%)(100)

The amount of antifreeze in the total solutions is (80%)(x+100)

Now write the equation from the information provided,

(90%)x + (10%)(100)= (x+100)(80%)

0.9x + (0.1)(100)=(x+100)(0.8)

0.9x + 10 = 0.8x+ 80

0.1x =70

x = 700

700 gallons of 90% antifreeze solution should be added.

Check,

(90%)(700)+ (10%)(100)= (700+100)(80%)

630 + 10 = 800(0.80)

640 = 640