What is -4x *x because i can't figure it out

Brent wants to know what is 5 x 1/2

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

Onnie is considering doing some long term investing with money that she inherited. she would like to have $50,000 at the end of 30 years. approximately how much money would lonnie need to put into an account earning 6% interest compounded annually in order to meet her goal?