PLS HELP! INCLUDING THE FOLLOWING QUESTIONS BELOW TY!

Find the solution of this system of equation -7x+y=-20 9x-3y=36

In the field of thermodynamics, rankine is the unit used to measure temperature. one can convert temperature from celsius into rankine using the formula , what is the temperature in celsius corresponding to r degrees rankine? a. 9/5(c - 273) b. 9/5(c + 273) c. 5/9( c - 273) d. 5/9( c + 273)

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?