273+416 will give you the sum of 688. so you take your answer and subtract it from the previous question. either way you should get the other number to the equation (for example) 688-416=273 or 688-273=416 to check her addition work she should've subtracted her answer from a previous number she used in her addition problem.
Well the volume of a cube is lbh that is length×breath×height which is given to be equal to 672.5cm3 thus lbh=672.5cm3 lb×10cm=672.5cm3 (putting value of h) solve and u obtain the Base area! (lb)