Which equation is equivalent to the formula r = st? t equals s over r t = rs s equals r over t s = rt

If you had $1,900,000, how many days would it take you to spend all if you spent $1 a second. (there are 86,400 seconds in a day)

Ten times the square of a non-zero number is eqaul to ninety times the number

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.