Answer:
x= 20
Step-by-step explanation:
The sum of the three angles is 90 degrees
x+2x+x+10 = 90
Combine like terms
4x+10 = 90
Subtract 10
4x+10-10 = 90-10
4x= 80
Divide by 4
4x/4=80/4
x = 20
 
        
             
        
        
        
Step 1. (5+4-2)x(-2)
Step 2. (7)x(-2)
Step 3. -14
        
             
        
        
        
171 minutes 
Explanation:
6 is the initial cost, .08 is the cost per minute and 19.68 is the total, set up an equation that looks like this: (x is the unknown variable)
6+.08x=19.68
19.68-6=13.68
.08x=13.68
.08x/.08=x
13.68/.08=171
x=171
        
             
        
        
        
The two numbers are 41 & 37.
The way to solve this is by setting up an equation. We know that 2 numbers are going to equal 78, so here would be the general equation (let x represent the number we don't know): 
(x) + (x + 4) = 78
Now, we need to simplify it (combine like terms):
2x + 4 = 78
Then you can solve it like any other equation. Subtract 4 on both sides:
2x = 74
Divide by 2 on both sides:
x = 37. 
So, now you know one number is equal to 37 and that the other is 37 + 4.
That's how you get 37 & 41.