4(2x +5) = (8x + 20)
8x =20 is an equivalent expression
The answer is both all real numbers less than 0 and all real numbers greater than 0
The trick to calculating the area here is to subdivide the diagram into smaller parts. For example, there's a 3 cm-by-3cm square. The rectangle is 4 cm by 8 cm.. The triangle has a base of 5 cm and a height of 3 cm.
Total area = area of square + area of rectangle + area of triangle
= 9 cm^2 + 32 cm^2 + (1/2)(5 cm)(3 cm)
= (9 + 32 + 7.5) cm^2
= 48.5 cm^2 (total area of figure)
There's a catch here, and I don't really want to go into full detail. Because of
this catch, I think it would be unusually tough to write a simple equation for this
situation. If you wouldn't mind, let's just list it instead:
<u>After</u> . . <u>water added</u> . . <u>total in pool</u>
7 min . . . 14 gallons . . . 14 gallons
1 more . . 1 gallon . . . . . 15 gallons
7 more . . 14 gallons . . . 29 gallons
1 more . . 1 gallon . . . . . 30 gallons
5 more . . 10 gallons . . . 40 gallons, the pool is full
Add up all the minutes: <u>21 minutes</u>
