Can we use the modified equation to find the value of the variable in solving simultaneous equations? If no is there any exception?

Nine more than four times a number is the same as one less than twice the number. find the number?

Prism m and pyramid n have the same base area and the same height. cylinder p and prism q have the same height and the same base perimeter. cone z has the same base area as cylinder y, but its height is three times the height of cylinder y. the figures and have the same volume.

Cody ran nine miles on his first day of training. the next day he ran 1/8 that distance. how far did he run the second day?