Answer:
2(-2)-5(-2)+12
-4-(-10)+12
6+12
18
Step-by-step explanation:
Answer:

round off to 3s.f
means change to when you have 3 useful numbers
7613.83 has 4numbers.2decimal
same must be the round off value
Answer:
a = 21
b = 63
c = 42√3
d = 21√3
Step-by-step explanation:
The sides of a 30°-60°-90° triangle have the ratios 1 : √3 : 2. The given side (42) is the longest side of the smallest triangle, and the shortest side of the largest triangle.
That means the other sides of the smallest triangle will be ...
a = 42/2 = 21
a+b = 2(42) = 84
b = (a+b) -a = 84 -21 = 63
d = 21√3 . . . . middle-length side of the smallest triangle
c = 42√3 . . . . middle-length side of the largest triangle
The values of the variables are ...
- a = 21
- b = 63
- c = 42√3
- d = 21√3
Find a common multiplier then divide ex. 21/27 = 7/9
There are 80 children. 45 of them are girls. The amount of boys is equal to:

That means there are 45 girls and 35 boys.
The ratio of boys to girls is: 
Simplify:

Your answer is 7:9