Brad, lance, allen, and john are all brothers. they are measuring and comparing their heights. they have found that lance is exactly 1 foot taller than brad and john is exactly 1 foot taller than allen. they also found that the product of brad's and lance's heights is equal to allen's height and if they subtract 1 foot from both brad's and lance's height, the product is equal to john's height. create a system of equations to model the situation above, and use it to determine if there are any solutions. if there are any solutions, determine if they are viable or not. there is only 1 solution, and it is viable. there are 2 solutions, and only 1 is viable. there is only 1 solution, and it is not viable. there are no solutions.