Explain how you can rewrite the equation n+8=24 so that it involves subtraction rather than addiction

Which expression is equivalent to the expression shown?

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details