Answer:
1) y = - 0.54(25)
2) 0.4 = 98 - 0.54t
3) 0.6 = 2 + 0.54t
4) 98 - 0.54t = 2(2 + 0.54t)
(you asked for equations, so I think these are the equations you are looking for!)
Explanation:
1)
(given) y = 98 - 0.54t
(plugging in years after 1960) y = - 0.54(25)
2)
(given) y = 98 - 0.54t
(changing percent to decimal) 40% = 0.4
(plugging in percentage) 0.4 = 98 - 0.54t
3)
(given) y = 2 + 0.54t
(changing percent to decimal) 60% = 0.6
(plugging in percentage) 0.6 = 2 + 0.54t
4)
(given)
(male) y = 98 - 0.54t
(female) y = 2 + 0.54t
(setting up the equation so male is 2 times the percent of female)
98 - 0.54t = 2(2 + 0.54t)