PLSSS HELP & pls dont write something random to get points

What is the value of x in the equation7x+2y=48 when y=3

What is the simplified form of square root of 400 to the 100th power ?

20 points for the answer. this is for real , don't put random ! a rectangle has a length of 4 centimeters and a width of 7 centimeters. what is the effect on the perimeter when the dimensions are multiplied by 5? the perimeter is increased by a factor of 5. the perimeter is increased by a factor of 20. the perimeter is increased by a factor of 25. the perimeter is increased by a factor of 100.