What is the prime factorization of 21•10

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

The spring the owner of a sporting good store decreases the price of winter gloves from $10 to $8 each increases the price of swimming goggles from $8 to $10 without doing the math you think the percent decrease in the price of the gloves the same as the percent increase of the goggles explain why or why not

Anna is constructing a line segment that is congruent to another segment ab. for the construction, which tool should be used to mesure segment ab