Solve for x: 2 over 5 (x − 4) = 2x.

x=-1

Step-by-step explanation:

2/5(x-4)=2x

Multiply both sides by 5

2(x-4) = 10x

2x-8=10x

-8=8x

-1=x

Check :

2/5(-1-4) = 2*-1

2(-1-4)= -10

-10 = -10

For this case we must solve the following equation:

We multiply on both sides by 5x-20:

We apply the quadratic formula:

Where:

So:

Thus, we have two roots:

x = 10.1

step-by-step explanation:

all of the angles of a tirangle add up to 180º

180 - 65 = 115 (since we already know the value of one angle)

(2x + 7) + (8x + 7) = 115

(combins like terms) 10x + 14 = 115

(isolate the variable subtract 14 from both sides): 10x = 101

(find the variable divide both sides by 10): x = 101/10

x = 10.1