Answer:
Randy is 48 years old
Sandy is 12 years old
Todd is 27 years old
Step-by-step explanation:
Given
Represent their ages with the first letters of their names:
[tex]R + S + T = 87[/tex]
[tex]R = 4 * S[/tex]
[tex]T = 15 + S[/tex]
Required
Determine their individual ages
We'll solve the above equations using substitution method of simultaneous equations
Substitute 15 + S for T and 4 * S for R in [tex]R + S + T = 87[/tex]
This gives:
[tex]4 * S + S + 15 + S = 87[/tex]
[tex]4 S + S + 15 + S = 87[/tex]
Collect Like Terms
[tex]4 S + S + S = 87 - 15[/tex]
[tex]6S = 72[/tex]
Divide through by 6
[tex]S = 72/6[/tex]
[tex]S = 12[/tex]
This implies that Sandy is 12 years old
Substitute 12 for S in [tex]R = 4 * S[/tex] and [tex]T = 15 + S[/tex]
[tex]R = 4 * 12[/tex]
[tex]R = 48[/tex]
[tex]T = 15 + 12[/tex]
[tex]T = 27[/tex]
This implies that Randy is 48 years old and Todd is 27
