I'm guessing you have to balance these.
I took a picture of my working out.
Answer to the first one = 2HCl+CaCO3=CaCl2+H20+CO2
So basically just add a big 2 in front of the first HCl
Answer to second one = 2Ni + O2 = 2NiO
So basically in this one just add a big 2 in front of both of the Ni
