Answer:

Step-by-step explanation:
hope this helps:)
Answer:
see the explanation and the attached figure
Step-by-step explanation:
we have
----> given
Divide by -2 both sides
----> by Division Property of Equality
Simplifying

Subtract 1 both sides
----> by Subtraction Property of Equality
Simplifying

He can make 15 chess boards.
All you need to do is multiply 3 by 5.
Answer:
11
Step-by-step explanation:
The mean is calculated as
mean = 
let the third number be x , then
= 15 ( multiply both sides by 3 to clear the fraction )
34 + x = 45 ( subtract 34 from both sides )
x = 11 ← third number
Simplify both sides of the equation
-25(x-4)=-55(x-10)
(-25)(x) + (-25)(-4)=(-55)(x) + (-55) (-10)
Distribute
-25x+100=-55x+550
Add 55x to both sides
-25x+100+55x=-55x+550+55x
30x+100-100=550-100
subtract 100 from both sides
30x+100-100=550-100
30x=450
divide both sides by 30
30x/30=450/30
x= 15
The value of x is 15
I hope that's help you my friend !