3) How many grams of SALT must be added to 40 grams of a 28% salt solution to obtain a 40% salt solution?

A 40-g solution of concentration 28% salt contains

0.28 (40 g) = 11.2 g

of salt.

To get a solution with concentration 40%, suppose you add x grams of salt. Then this new solution has a new total mass of (40 + x) g and contains (11.2 + x) g of salt. At 40% concentration, we have

(11.2 + x)/(40 + x) = 0.40

Solve for x :

11.2 + x = 0.40 (40 + x)

11.2 + x = 16 + 0.40x

0.60x = 4.8

x = 8

step-by-step explanation: 4 cause 2+2=4