A bike shop sells rolling strollers for runners with babies, with a total of 28 in the store. Some of the strollers have 3 wheels and some have 4. If there are 100 wheels, how many 3-wheel strollers are there?
A.
25
B.
12
C.
3
D.
16

Question

A bike shop sells rolling strollers for runners with babies, with a total of 28 in the store. Some of the strollers have 3 wheels and some have 4. If there are 100 wheels, how many 3-wheel strollers are there?
A.
25
B.
12
C.
3
D.
16

anonymous · Answer

x= 3 wheels
y = 4 wheels
x+y=28
y=28-x
3x+4y=100
3x+4(28-x)=100
3x+112-4x=100
-x=-112+100 
Add 100 to -112 to get -12.
-x=-12 
multiply by -1
x=12