"Girls, this is my brother."
Translation:Девочки, это мой брат.
Based on the tips, words ending in -a/-я can change to either -ы/-и when they become plural, but Russian has a rule that if the letter prior to the vowel is к, г, х, ш, ж, щ, or ч, then it must change to -и. There's a similar rule for choosing from -а, -у, -я, or -ю after a consonant: after к, г, х, ш, ж, щ, ч, and ц, you must use -а or -у.
Folks, if I don't have a Cyrillic keyboard enabled on my smartphone , so I can't type the correct response, in Cyrillic, to some of these questions. I can phoneticize it in English, but the exercise won't let me go any further. You all need to fix this with another option or just rely on letter recognition.
Try "Swiftkey" app. from Google Play Store. It allows you to switch quickly & effortlessly between 5 languages at a time, plus it is very cool looking & customizable for more languages & keyboard styles.
I have used it while learning 8 languages by switching back and forth -5 at a time though is quite comfortable.