Answer:

Step-by-step explanation:
So we have the equation:

First, distribute the left side:

Add values on the left side:

Add 7 to both sides. The right side cancels:

Subtract 2x from both sides. The left side cancels:

Divide both sides by -6:

Therefore, x equals -3.
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
Move the decimal point to the right one place value.
1.7 x 10 = 17
17 is your answer
hope this helps