P = pizza and c =cakes
Last week: 8p + 13c = 134
Today: 28p + 4c = 220
Let’s take the formula for today and subtract 28p from each side to isolate the 4c.
4c = 220 - 28p
Now divide each side by 4
c = (220 - 28p)/4
Simplify to c = 55 - 7p
Now go to the formula for last week, substitute the c for 55-7p
8p + 13(55 - 7p) = 134
8p + 715 - 91p = 134
Simplify to 715 - 83p = 134
Let’s add 83p to each side.
715 = 134 + 83p
Subtract 134 from each side
581 = 83p
Divide each side by 83
p = $7
Hello!
The answer is 96 words.
He can type 32 words every 30 seconds, 64 words for 60 seconds or 1 minute and 96 words for 90 seconds.
:)