You are basically adding like terms. For example for the first expression, it is 7x^2 + 2x^2, which equals 9x^2. Remember since you're adding, do not add the exponents.
10xt=190 T represents the amount of trips and 10 represents the amount of money she spends each trip. Since she has $190 already it will be on the other side of the equation after the equal sign
