From the condition, you have these equations  (I write them as I read)


    t + c + d = 1750     (1)

    c = 2t,              (2)

    d = t + c + 100.     (3)


Substitute expression (2) into equation (2). You get then


    d = t + 2t + 100 = 3t + 100    (4)


Now substitute (2) and (3) into (1) to get


    t + 2t + (3t+100) = 1750,

or

    6t                = 1750 - 100 = 1650.


Hence,  t = 1650/6 = 275.


From this point, complete the solution on your own.