A=1/2b(h) this is the formula to find the area of a triangle
18. s = 5r^2 + 7......making r the subject
s - 7 = 5r^2
(s - 7) / 5 = r^2...by taking the sqrt of both sides, it eliminates the ^2
( sqrt (s-7)/5) = r
19. h = ut - 1/2gt^2....u = 100, t = 1 4/5(or 9/5)...g = 6.4
h = (100)(9/5) - 1/2(6.4)(9/5^2)
h = 180 - 1/2(6.4)(3.24)
h = 180 - 3.2(3.24)
h = 180 - 10.368
h = 169.632 or 169 79/125
20. sorry..do not know this one
2 cups of dog food is 194 grams and 3 cups is 291 grams.
The dog needs 220 grams. So at most 3 cups of dog food. Wish I could simplify more but I can't. sorry.
x − y = 0 = difference
x + y = 4 = sum
Can be solved by the sum and difference rule (most of the time without pen and paper)
x=(sum+difference)/2=0+4/2=2
y=(sum-difference)/2=(4-0)/2=2
