Simplify the expression.
a) 2 (5 - x) + 3. 10 + x
b) 4x – 3(x + 7) -21
c) (2x – 1) (2x - 1) 4.22.4x +1
d) (2x – 1) (3x + 5) 6x² + 7x –

The perimeter of a stage is 116 feet. it is 17 feet wide. how long is it?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

He mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?