Question

100 POINTS!!!

Explain which method you used for solving the system of equations in which x represents the number of bottles of water sold and y represents the number of sandwiches sold. x + y = 390 and 2x + 4y = 1260

Answer 1

you would double the x+y=390 so you have 2x + 2y = 780

you’d take those away to be left with
2y = 480
y = 240

you’d then substitute y into the equation

x + 240 = 390
x = 150


This is called a simultaneous equation

Answer 2

x=150

y=240

Explanation:

*Use simultaneous equation solving

1.Label your equations

x+y=390......1

2x+4y=1260......2

*make one of the unknowns subject of formula, to form equation 2

x=390-y.....3

*sub.3 into 2

2(390-y)+4y=1260

780-2y+4y=1260

2y+780=1260

y=240

sub. y into 3

x=390-y

x=390-240

x=150