"Write a balanced nuclear equation for the beta decay of each of the following" HELP PLEASE?

A.)
25/11 Na → 25/12 Mg + 0/-1 e

B.)
20/8 O → 20/9 F + 0/-1e

C.)
92/38 Sr → 92/39 Y + 0/-1 e

D.)
60/26 Fe → 60/27 Co + 1/-1e

A clearer presentation is shown below :
https://c1.staticflickr.com/9/8813/28037924343_468f3ab0f6_o.png

[25/11] Na
When it beta decays it emits an electron from the nucleus.
This comes about by an neutron disintegrating into a proton and emitting an electron.
Hence the mass (25) stays the same but we have gained a proton (11 ==> 12) and lost a neutron.
Hence the new elemental isotope is [25/12] Mg .

Do the remainder the same.

Strontium- 92 . ==> [ 92/38]Sr '92' is the isotopic mass. Similarly with iron-60.