Answer:
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Please give brainliest
Answer:
Given the statement:
9 less than the sum of x and 5
"Sum of x and 5" means 
"
" means subtract
then;
the statement 9 less than the sum of x and 5 becomes;
⇒
⇒
Therefore, the expression for the given statement is
The length is 486
Step-by-step explanation:
638 subtract 152
Assume Josh made X cupcakes; Alice made Y cupcakes; Tom made Z cupcakes.
Josh made 10 more cakes than Alice so,
X = Y + 10 ---- 1st Eqn.
Alice made 8 more than Tom so,
Y= Z+8 --- 2nd Eqn.
Total cakes = 62 so,
X+Y+Z = 62 ---- 3rd Eqn.
by solving three equations we get X= 30; Y= 20; Z=12.
So Tom made 12 cupcakes
X = 5, that’s the answer to question 12
