How do you know which operation to use when solving an algebra equation?

Step-by-step explanation:

In other words, in any math problem you must start by calculating the parentheses first, then the exponents, then multiplication and division, then addition and subtraction. For operations on the same level, solve from left to right.

PEMDAS

Step-by-step explanation:

P.      parentheses

E.      Exponents

M.     Multiplication

D.      Division

A.       Addition

S.        Subtraction

when doing algebra you start from the top and go down if there aren’t any of one thing go to the next.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

f(x) = - 2/3x + 5; f(5/2)

substitute 5/2 in for x:

f(5/2) = -2/3(5/2) + 5

simplify the right side:

f(5/2) = -5/3 + 5

f(5/2) = 10/3

answer:

f(5/2) = 10/3

i hope this you!