Tom's weight is 20 pounds less than twice carl's weight. if together tom and carl weigh 340 pounds, how much does tom weigh?

T = Tom's weight

c = Carl's weight

we know that twice of Carl's weight equals Tom's weight + 20 pounds so

2c = t+20

and we know that Tom's weight + Carl's weight = 340

t+c = 340

then from there you can solve using substitution or elimination