There are two ways, calculator and tables.  I'll explain both.

If you have a TI-83 or TI-84 calculator and are allowed to use it,

press 2nd, then vars, then 2.  If your calculator is newer, you'll see the
"wizard" screen.  Make it read like this:

       normalcdf
lower:-0.78 
upper:99999999
μ:0
σ:1
Paste

Scroll down to Paste and press enter.
You will read

normalcdf(-0.78,99999999,0,1)

(If your calculator is old, make it read like the previous line):

Then press enter.

You will read
0.7823046313 
Round to 0.7823

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There are two kinds of normal tables in use today.  If your table is like the one on this site:

http://www.z-table.com/

Find -.07 in the leftmost column headed z, then go across to the column
headed .08 and read the value .2177.  Since this table reads the area to
the left, this value is P(z < -0.78).  But we want P(z > -0.78), so we
must subtract from 1 and get 1-.2177 which is 0.7823.

--------------------------------

If your table is like the one on this site:

 https://www.mathsisfun.com/data/standard-normal-distribution-table.html

Find 0.7 in the leftmost column headed z, then go across to the column
headed 0.08 and read the value 0.2823. Since this table reads area to the
right of the middle, this value is P(0.5 < z < 0.78).  By symmetry of the
normal curve, that is the same as P(-0.78 < z < 0.5).  But we want 
P(z > -0.78), so we must add 0.5 which is P(z > 0.5).  We get 0.5+0.2823
and get 0.7823.

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Regardless of how you get it, the answer is 0.7823.

Edwin