Hey there!
The main concept of pre-algebra is solving equations for variables in them.
For example, let's say you have the algebraic equation below.
x+1=3
With algebra, you need to figure what x is equal to. To do so, you will use inverse operations on both sides of the equation to isolate x one side, showing what it is equal to.
We would subtract 1 to both sides to isolate x on one side.
x+1-1=3-1
As you can see, +1-1=0, therefore, this would give us x+0, or just x. Now it is isolated and will show us what it is equal to.
x=3-1
x=2
Therefore, in our equation x+1=3, x would be equal to 2.
I hope this explanation helps! Have a great time here at Brainly!
Answer:
20
Step-by-step explanation:
If the two triangles are similar, then corresponding sides must share a constant ratio. This means that:

Let's use the second ratio:

Multiply both sides by 12:

Hope this helps!
isosceles trapezoid
....................................
The pie chart is a percent pie chart.
Silicon is 28% of the earth crust = 28/100 = 7/25.