Answer:
16.
How to find... ↓
The small triangle is 1/3 size of the big triangle.
If this is the case, find the LCF here, 4, and multiply each angle's value by the least common factor, 4.
3 x 4 (bottom) = 12
5 x 4 (right side) = 20
4 x 4 (left side <em>the missing side) </em>= 16
Therefore,
The missing side value, <em>x</em>, is 16.
They are algebraic symbols or known as unknown number. There is no true value for them. The value of algebraic symbols are based on equations
ie. 1+x = 2
First, we isolate the x by canceling the +1 FROM BOTH SIDES(Balance method) by -1 ON BOTH SIDES.
1+x-1 = 2-1
So we are left with the x on the left side, and a single number on the right side. Therefore, our calculation is complete.
x = 1
More complex cases would be
2y-3 = 45
First, we need to isolate the algebraic symbol, which is 2y (yx2) by +3 ON BOTH SIDES
2y-3+3 = 45+3
2y = 48
WE ARE NOT DONE! 2y=48 is still an equation. Therefore, to isolate the y, we need to divide BOTH SIDES by 2
2y/2 = 48/2
y = 24
There is no true or absolute or definite value for algebraic symbols like x,y,z,a,c,t,h,d etc. They are used to represent unknown numbers.
Hope this helped!
Scientific notation is a way to write compactly numbers with lots of digits, either because they're very large (like 2393490000000000000000000), or very small (like 0.0000000000356).
We use powers of ten to describe all those leading/trailing zeros, so that we con concentrate on the significat digits alone.
In your case, the "important" part of the number is composed by the digits 6 and 1, all the other digits are zero. But how many zeroes? Well, let's do the computation.
Every power of 10, 
is written as one zero followed by n zeroes, so we have
Multiplying a number by means to shift the decimal point to the right and/or add trailing zeroes n times. So, we have to repeat this process six times. We shift the decimal point to the right one position, and then add the five remaning zeroes. The result is thus
