Oh the wrong answer got deleted so here I am :)
Set up a system of equations. Let's make battery B and solar S where B and S represent the number of units.
Step 1: The first two sentences talk about assembly.
For Battery, it would be 10B.
For Solar, it would be 15S.
If you add 10B and 15S, it would take about 450 min total:
10B+15S=450
Step 2: Now for the second equation. Both take 8 min, so 8B + 8S = 280 min.
Step 3: Solve for a variable. Let's do the second equation.
8B + 8S = 280 Subtracted 8B from both sides.
8S = 280 - 8B Divided both sides by 8 to get S by itself.
S= [tex] \frac{280}{8} [/tex] - B
S = 35 - B Simplified, 280 divided by 8 = 35.
Now plug in S into the first equation.
10B + 15S = 450
10B + 15(35-B) = 450
10B + 525 - 15B = 450
-5B = -75
B=15
Then you can plug in 15 for either of the first two equations to get S.
10B+15S=450
10(15)+15S=450
S=20
So 15 battery powered units and 20 solar powered units.
