Answer - 13.098 gm
Description -
Dear student,
As we know 
⇒ Mass = Density * Volume
so multiplying given Volume with the Density of gold ,we can calculate the mass of the gold . Density of gold at room temp. is 19.32 grams per cubic centimeter.
so mass of the sliver of gold = 19.32 * 0.678 = 13.098 (ans)
The metric system originated in France in 1799 following the French Revolution although decimal units had been used in many other countries and cultures previously. Although there have been many different measurements and the definitions of the units have been revised, the official system of measurements of most countries is the modern form of the metric system which is known as the "International System of Units".
Its called equivalent fractions when you have a whole fraction
3(v + 2) + 4 = 13
Mutiply the bracket by 3
(3)(v)= 3v
(3)(2)= 6
3v+6+4= 13
3v+10=13
Move +10 to the other side
Sign changes from +10 to -10
3v+10-10= 13-10
3v= 13-10
3v= 3
divide both sides by 3
3v/3= 3/3
v= 1
Answer : v= 1