At first, you have to make an equation to represent both of their weights together. A= Aiden's weight. 30+3A+A=210. You want to add like terms so that is comes out to 30+4A=210. You want to subtract 30 from both sides; 4A=180 Divide 4 on both sides; A=45 Aiden weighs 45 pounds. You have to multiply 45 by 3 and add 30; 165 165+45=210 Equation: 30+ 3A+A=210; 30+4A=210 Aiden: 45 pounds Jonathan: 165 pounds