X^2-y^2=55
this means that
(x+y)(x-y)=55
we know that x-y=11 so we can write
(x+y)(11)=55
x+y=55/11 we divide by 11 and we obtain
x+y=5
x-y=11 this means
x=y+11 we replace in the other equation (x+y=5)
y+11+y=5
2y=5-11
2y=-6
y=-3
and you find out that also
x=8
Answer:
A. 13%
Step-by-step explanation:
let's suppose there's 1000 bars of chocolate in general
70 % dark = 700 dark choco bars
30 % milk = 300 milk choco bars
20 % have nuts = 200 bars have nuts
80 % don't have nuts = 800 bars don't have nuts
if 90 % of dark chocolate bars don't have nuts, that means 630 dark chocolate bars don't have nuts, but 70 have nuts
200 bars in general have nuts, if only 70 dark chocolate bars have nuts,
200 - 70 = 130
130 = 13%
