1. ## simultaneous equations

i got given this question

solve the following simultaneous equations showing all your working out substitute your answers to check them at the end

y= 20x - 15

y + 30x = 60

can someonbody tell me if how to do this question and wheter it means work each individual question out or both of them

2. You replace y in the second equation
$y + 30x = 20x - 15 + 30x = 50x - 15 = 60$
$50x = 75 \implies x = \frac{3}{2}$

3. Originally Posted by jm16
i got given this question

solve the following simultaneous equations showing all your working out substitute your answers to check them at the end

y= 20x - 15

y + 30x = 60

can someonbody tell me if how to do this question and wheter it means work each individual question out or both of them

$(1)y= 20x - 15$

$(2)y + 30x = 60$

y in (1) is isolated, therefore use the method of substitution to solve(plug the value of y in (1) to y in (2)

$20x-15+30x=60$

$50x=75$

$x=1.5$

substitute this x value back into (2) to solve for y

$y+30(1.5)=60$

$y+45=60$

$y=15$

Checking

(1)

$15=20(1.5)-15$

$15=15$

(2)

$15+30(1.5)=60$

$60=60$

$\therefore$ the lines intersect at $(1.5,15)$