محو التحدي Σο (4η + 5) = c) 6 b) 19 c) 20 d) not one of the previous answers a

A crime-scene investigator has 3.4 ounces of a sample. He needs to conduct four tests that each require 0.6 ounces of the sample, and one test that requires 0.8 ounces of the sample. How much of the sample remains after he uses it for the five tests?

Solve: 4(q+2)3q=8 .

Given that 2x3=7. What reason allows the conclusion 2x=10?