The first step here would be to write an equation for this problem.
4

+ 3

= ?
Now that we have our equation, we can solve it. But rather than converting both the mixed fractions into improper fractions, there is a simpler way we can solve.
We can separate the equation into two simple equations. Which will be adding both the whole numbers and then both the fractions
4 + 3 = ?

+

= ?
Now we solve.
4 + 3 = 7

+

=

Now that we solved both our separate equations we can get our final answer by combining both answers.
7

Notice how our answer can be simplified because when both the numerator and denominator are the same, they equal one whole.
After converting

to one whole we will get our final, simplified answer.
7

= 8
So both
Sarah and Nathan picked 8 buckets of strawberries.