How do u add and subtract decimals ?

Mr. thompson is on a diet. he currently weighs 260 pounds. he loses 4 pounds per month. what part of the story makes the relationship not proportional?

Calculate the average rate of change over the interval [1, 3] for the following function. f(x)=4(5)^x a. -260 b. 260 c. 240 d. -240

Dots sells a total of 279 t-shirts ($2) and shorts ($4). in april total sales were $670. how many t-shirts and shorts did dots sell?