Estimate the product. Round each factor to the nearest whole number, and then multiply. 6.7 × 4.3

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of

If f(x) = 4x - 3 and g(x) = x + 4, find (f - g) (x)

Can someone, me with this. i really need with this