Express 4,400 in scientific notation

What is 1/2 x (6 x 4)+3 + 2 show your work

Segment xz is bisected by point y. if xy = 12x, and the measure of xz = 18x – 6, solve for x

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