Let x = cans of paintLet y = rollers

Question

equation for this problem To paint his house, Samuel bought 2 cans of paint and one roller for $30. When friends came over to help, he went back to the store and bought three more cans of paint and two more rollers for $50 How much did he pay for a roller?

Answer 1

  2c +   r = 30 , let's multiply this equation by 2 
  4c + 2r = 60
—    
  3c + 2r = 50   
    c + 0  = 10 ---> 1 can of paint cost $10
2 * 10 + r = 30 ----> 1 roller cost $10 too