Answer: t = 7
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Step-by-step explanation:
If we replace every copy of x with t, then we go from this
F(x) = 3x+5
to this
F(t) = 3t + 5
All we've done really is change the letter. We still are dealing with a variable. We're told that F(t) is equal to 26, which would allow us to replace the "F(t)" with "26" in the second equation above.
So we now have the equation 26 = 3t+5 which is the same as 3t+5 = 26
Let's solve for t
3t+5 = 26
3t = 26-5 .... subtract 5 from both sides
3t = 21
t = 21/3 .... divide both sides by 3
t = 7 is the answer
Now note that...
F(t) = 3t + 5
F(7) = 3*7 + 5 .... replace t with 7
F(7) = 21 + 5
F(7) = 26
This means we got F(t) = 26 when t = 7
It's the same as saying x = 7 leads to F(x) = 26.
This helps confirm we have the correct answer.