Iodine-131, a radioactive substance that is effective in locating brain​ tumors, has a​ half-life of only 8 days. A hospital purchased 24 grams of the substance but had to wait seven days before it could be used. How much of the substance was left after seven ​days?

you have to find the same variables -3n - 5n so this would be -3n +(-5n) which equals -9n

b) yes

step-by-step explanation:

let the statements be named as,

statement 1: if the power has been cut, then the refrigerator does not work.

statement 2: the refrigerator does not work.

conclusion: the power has been cut

now, 'law of detachment states that if we have the statements given as,

1. if p, then q.

2. p

then, we get the true statement or conclusion as q'.

thus, on comparing, we get that,

p: if the power has been cut.

q: the refrigerator does not work.

so, the argument is true by the law of detachment.

using the formula for pythagorean theorem (a2+b2=c2)(the twos are exponents), and knowing that you have b squared and c squared, just reverse it. 26 squared minus 10 squared equals c squared. 26 squared is 676 and 10 squared is 100. you get 576, then use your square roots to undo the squared numbers to get 24.