To model half-life, use the formula

. Here,

is the amount remaining after a length of time

.

is the amount that you start with.

is the half-life. You plug in 50 for

, 10 for

, and 25 for

. You get

.
Step-by-step explanation:
20a + 158+6c=you will expand the brackets
= so it is 120+60+48
20a+158+6c=120+60+48
20a+ 6c=120+60+48-158
20a+6c=70
20a divide by 20+6c divide by 6 on both side
a + c = 0.58
Answer:
figuring it out now
Step-by-step explanation: