Question

Mrs.Jackson is filling planter boxes with soil. She has soil that is 27% sand and she buys 8 pounds of a commercial potting soil that is 16% sand. She mixes some of her soil with the 8 pounds of commercial potting soil. The resulting soil mixture is 19% sand. How many pounds of her soil did she use?

Answer 1

(27x + 16*8)/x+8 = 19

(27x +128) /x+8 = 19

multiply both sides by x+8

27x+128 = 19x +152

subtract 19x from both side:

8x +128 = 152

subtract 128 from both side:

8x = 24

divide both sides by 8

x = 24 /8

x = 3 pounds