Answer:
M = 84
V = 1.89
Step-by-step explanation:
We are given the formula:
D = M/V
Where D is the density, M is the mass, and V is the volume of a substance.
(a) We'll use transposition to make M the subject of the equation.
To isolate M, we need to multiply by V on both sides of the equation:
D*V = M/V * V
The right side of the equation simplifies:
D*V = M
Now we swap sides:
M = D*V
Substituting the given values of V=12 and D=7:
M = 7 * 12 = 84
M = 84
(b) Now we must make V the subject of the equation:
D = M/V
Again, we multiply by V:
D * V = M
Now divide by D:
V = M/D
Substitute M=3.4, D=1.8:
V = 3.4/1.8
V = 1.89