Can someone please help

What is the result of adding the system of equations? 2x+y=4 3x-y=6

Maria found the least common multiple of 6 and 15. her work is shown below. multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, . . multiples of 15: 15, 30, 45, 60, . . the least common multiple is 60. what is maria's error?

The length of a rectangle plus its width is 24 cm. the area is 143 square cm. what are the length and width of the rectangle?