Joe has three times as many as Tom,
So J = 3T
and Tom has four times as many as Mary.
So T = 4M
Altogether they have 153.
J+T+M = 153
So we have this system of three equations:
Substitute 4M for T in J=3T
J=3T
J=3(4M)
J=12M
12M for J, and 4M for T in J+T+M = 153
12M+4M+M = 153
17M = 153
M = 9
Substitute 9 for M in J = 12M
J = 12M
J = 12(9)
J = 108
Substitute 9 for M in T = 4M
T = 4M
T = 4(9)
T = 36
How many has each?
Joe has 108, Tom has 36, and Mary has 9.
Edwin