A+b+c=28x+40=180
—>28x=140
—>x=140/28=5
c=9x-3
—>c=42
You can, it's not as hard as you might think
simply multiply the speed by the fraction of time
23 × 1/5 = 23/5 = 4 3/5 = 4.6
She can only make 2 trail mixes
3x+2y=24
Times 2
6x+4y=48
-
6x+2y=30
=
2y=18
y=9
x=2. Hope it help!