The combined age of john and mary is 20 years. in 2 years, john will be five times as old as mary. how old is john at this time?

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?

The graph shows the distance kerri drives on a trip. what is kerri's speed?

Lola says these two expressions have the same value. expression a expression b which explains whether lola is correct?