Simplify $3t+4-6t+7t-4$.
To simplify an expression, I want to combine like terms and write it in a more compact form. Like terms are those that have the same variable and exponent, or are just constants. In this expression, I see that there are three terms that involve t: $3t, -6t,$ and $7t$. To combine them, I can add their coefficients, which are the numbers in front of the variable. So $3t-6t+7t$ becomes $(3-6+7)t$, which is $4t$. The other two terms are constants: $4$ and $-4$. To combine them, I can just add them together. So $4-4$ becomes $0$. Therefore, the simplified expression is $4t+0$, which I can write as just $4t$. 