Let a be Alvin's age and e be Elga's age. We have the following equations

- a = e - 12 ←younger means we subtract
- a + e = 60

(e - 12) + e = 60

2e - 12 = 60

2e - 12 + 12 = 60 + 12

2e = 72

2e | |

2 |

= |

72 |

2 |

e =

Plugging e = 36 into equation (1), we get

a = 36 - 12

a =