How do you know a number is divisible by 5?

Can some one explain how to slove specifically, what is the value of x? 0.9(x+1.4)-2.3+0.1x=1.6 enter the answer as a decimal in the box. x= ?

Maren is buying carpet for her rectangular living room. the room is 4.8 yards wide and 5.2 yards long. how much carpet does she need to buy? enter your answer as a decimal in the box. yd2

Do xuan nam isgoing to invest $1000 at a simple interest rate of 4% how long will it take for the investment to be worth $1040?