Distribute the 2 to get the pink box
10x + 2y = 18
Then if we are subtracting the bottom equation from the pink box
10x + 2y = 18
-(10x -7y = -18)
9y = 36
y = 4
Let
x ------> number of switch type A
y -----> number of switch type B
so
Remember that
1 hour=60 min
32 hours=32*60=1,920 minutes
4x+5y=1,920 -------> equation 1
3x+5y=1,740 ------> equation 2
Solve the system of equations
Solve by graphing
using a graphing tool
see the attached figure
Solution is
x=180
y=240
therefore
<h2>the number of switch type A was 180</h2><h2>the number of switch type B was 240</h2>
Well I believe that the answer is five. Simply because 10 divided by 5 is 2 and -15 divided by 5 is -3
A,B,D are your answers :)