HELP ASAP! I'm doing this for a test and need an answer asap! (brainliest)

Iwill make brain if you me correctly fill this out needs due today pls and send it back to me (click the link and you will get it)

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax